Here's More Proof That Fat Isn't As Bad As Dietitians Once Thought

NEW YORK (Reuters Health) - The types of fat people get in their
diet may not be as closely related to their risk of heart disease
as previously believed, a new review of past studies suggests.

Guidelines from the U.S. federal government and recommendations
from the American Heart Association call for increased
consumption of polyunsaturated fatty acids and lower consumption
of saturated fats.

But researchers found people's risk of heart disease varied
little based on how much of those fats they ate.

Polyunsaturated fats generally come from plant-based foods such
as nuts, seeds and vegetable oils. Omega-3 fatty acids, a type of
polyunsaturated fats, are found in fish.

On the other hand, most saturated fats in the American diet come
from foods of animal origin, including red meat and high-fat
dairy products.

The authors of the new review say uncertainties in evidence have
led to considerable variation in international guidelines on fat
intake. They also say the use of self-reported diet information
may have resulted in problems classifying the different fatty
acids that people eat.

"We intended to help resolve the existing uncertainties around
fatty acids and their potential association with coronary heart
disease risk," Dr. Rajiv Chowdhury told Reuters Health in an
email.

Chowdhury, from the University of Cambridge in the UK, led the
review that was published in the Annals of Internal Medicine.

He and his colleagues collected data from 72 previously published
studies of more than 600,000 people from 18 countries.

Those included studies that measured the types of fatty acids
people consumed or had in their blood, as well as those that
randomly assigned people to take fatty acid supplements or not.

All of the studies followed participants to see who developed
heart problems like heart attacks, heart disease or coronary
insufficiency.

When Chowdhury and his team analyzed data on fatty acid intake,
they found that none of the types of saturated or polyunsaturated
fats had a significant impact on heart disease risk. However,
consumption of trans fat - found in some processed foods and some
forms of stick margarine - was tied to a 16 percent increase in
risk. Guidelines call for avoiding trans fats altogether.

When the researchers examined markers of fatty acids in the
blood, they also found little difference in heart risk based on
levels of saturated or polyunsaturated fats. But the results
varied for individual fatty acids.

The researchers found that higher blood levels of two forms of
omega-3 fatty acids - docosahexaenoic acid (DHA) and
eicosapentaenoic acid (EPA) - were associated with a lower risk
of heart disease.

They did not see a significant reduction in heart disease risk
with any of the fatty acids in studies that randomly assigned
some participants to take them in supplement form. Doses used in
the studies ranged from 2 to 5.5 grams per day of added oils and
0.3 to 6 grams per day when capsules were used.

"The pattern of findings from this review did not support the
current cardiovascular guidelines that encourage high consumption
of total long-chain omega-3 polyunsaturated fatty acids and
suggest reduced consumption of total saturated fatty acids,"
Chowdhury said.

But he said further careful research and specifically large-scale
clinical trials are required before making a conclusive judgment
and changing dietary guidelines.

Linda Van Horn, from the Northwestern University Feinberg School
of Medicine in Chicago, told Reuters Health the study was well
done and demonstrated that some fatty acids are better than
others. But it's not enough to change current guidelines, she
added.

Van Horn chaired the 2010 U.S. Dietary Guidelines Advisory
Committee which was involved in creating federal recommendations
and is a spokesperson for the American Heart Association. She was
not involved in the new review.

"People need to eat as has been recommended - this paper changes
nothing about the adverse impact of saturated fat," she said.

Van Horn pointed out that there is no biological need for
saturated fats.

"People like their burgers and their hot dogs," she said, "but
this study still doesn't make them nutritious."